Transcript Lecture 2: Why are User Interfaces Hard to Design and Implement? and Types of User Interfaces Brad Myers 05-830 Advanced User Interface Software.

Lecture 2:
Why are User Interfaces Hard to
Design and Implement? and
Types of User Interfaces
Brad Myers
05-830
Advanced User Interface Software
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Why are User Interfaces Difficult
to Design?
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Why Hard to Design UIs?
“It is easy to make things hard. It is hard to make
things easy.”
 No silver bullet
 Seems easy, common sense, but seldom done
right
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Once done right, however, seems “obvious”
User Interface design is a creative process
Designers have difficulty thinking like users
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Often need to understand task domain
Can’t “unlearn” something
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Can’t Unlearn Something
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Why Difficult, 2
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Specifications are always wrong:
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"Only slightly more than 30% of the code
developed in application software development
ever gets used as intended by end-users. The
reason for this statistic may be a result of
developers not understanding what their users
need."
-- Hugh Beyer and Karen Holtzblatt, "Contextual Design: A
Customer-Centric Approach to Systems Design,“
ACM Interactions, Sep+Oct, 1997, iv.5, p. 62.
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Need for prototyping and iteration
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Why Difficult, 3
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Tasks and domains are complex
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Existing theories and guidelines are not
sufficient
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Too specific and/or too general
Standard does not address all issues.
Adding graphics can make worse
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Word 1 (100 commands) vs. Word 2007 (>2000)
MacDraw 1 vs. Illustrator
BMW iDrive adjusts over 700 functions
Pretty  Easy to use
Can’t just copy other designs
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Legal issues
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Why Difficult, 4
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All UI design involves tradeoffs:
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Standards (style guides, related products)
Graphic design (artistic)
Technical writing (Documentation)
Internationalization
Performance
Multiple platforms (hardware, browsers, etc.)
High-level and low-level details
External factors (social issues)
Legal issues
Time to develop and test (“time to market”)
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Why are User Interfaces Difficult
to Implement?
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Why Are User Interfaces Hard to
Implement?
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They are hard to design, requiring iterative
implementation
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They are reactive and are programmed from the
"inside-out"
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Not the waterfall model: specify, design, implement, test,
deliver
Event based programming
More difficult to modularize
They generally require multi-processing
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To deal with user typing; aborts
Window refresh
Window system as a different process
Multiple input devices
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Why Hard to Implement? cont.
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There are real-time requirements for handling input
events
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Output 60 times a second
Keep up with mouse tracking
Video, sound, multi-media
Need for robustness
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No crashing, on any input
Helpful error messages and recover gracefully
Aborts
Undo
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Why Hard to Implement? cont.
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Lower testability
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Little language support
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Primitives in computer languages make bad user interfaces
Enormous, complex libraries
Features like object-oriented, constraints, multi-processing
Complexity of the tools
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Few tools for regression testing
Full bookshelf for documentation of user interface frameworks
MFC, Java Swing, VB .Net, etc.
Difficulty of Modularization
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Example: reading a filename
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Readln() in Pascal, Java, C++, etc.
Vs. tool in modern toolkits
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Complexity of the file dialog itself
You must deal with aborting, undo, etc.
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Why Tools?
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The quality of the interfaces will be higher. This
is because:
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Designs can be rapidly prototyped and implemented,
possibly even before the application code is written.
It is easier to incorporate changes discovered through user
testing.
More effort can be expended on the tool than may be
practical on any single user interface since the tool will be
used with many different applications.
Different applications are more likely to have consistent
user interfaces if they are created using the same user
interface tool.
A UI tool will make it easier for a variety of specialists to be
involved in designing the user interface.
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Why Tools, cont.
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The user interface code will be easier and more economical to
create and maintain. This is because:
 There will be less code to write, because much is supplied by the
tools.
 There will be better modularization due to the separation of the user
interface component from the application.
 The level of expertise of the interface designers and implementers
might be able to be lower, because the tools hide much of the
complexities of the underlying system.
 The reliability of the user interface may be higher, since the code for
the user interface is created automatically from a higher level
specification.
 It may be easier to port an application to different hardware and
software environments since the device dependencies are isolated in
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the user interface tool.
Success of Tools
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Today’s tools are highly successful
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Window Managers, Toolkits, Interface Builders
ubiquitous
Most software built using them
Are based on many years of HCI research
Brad A. Myers. “A Brief History of Human Computer Interaction Technology.”
ACM interactions. Vol. 5, no. 2, March, 1998. pp. 44-54.
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What should tools do?
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Help design the interface given a specification of the tasks.
Help implement the interface given a design.
Help evaluate the interface after it is designed and propose
improvements, or at least provide information to allow the
designer to evaluate the interface.
Create easy-to-use interfaces.
Allow the designer to rapidly investigate different designs.
Allow non-programmers to design and implement user interfaces.
Provide portability across different machines and devices.
Be easy to use themselves.
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Tools might do:
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Provide sets of standard UI components
Guide the implementation
Help with screen layout and graphic design.
Validate user inputs
Handle user errors
Handle aborting and undoing of operations
Provide help and prompts
Deal with field scrolling and editing
Insulate the application from all device dependencies and the
underlying software and hardware systems.
Support features in the interface that allow the end user to
customize the interface.
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Types of User Interfaces
User Interface Styles
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Input Devices
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QUERTY keyboard (other types)
Mouse (1, 2 or 3 buttons)
Other pointing devices:
 Stylus or pucks on tablets or PDAs
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Issue: buttons, stability, etc.
"Light pens" on screens
 DataGloves, eye tracking, etc.
 “Bat" 3-D input device
 Stylus or finger on handheld
Speech input
Computer-connected camera & other sensors
 presence
 free-space gestures
 eye-tracking
Other physical objects (“phidgets”)
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Output Devices
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Older:
 TTY on paper
 24x80 terminals: "glass-TTY"
 Vector screens
Raster-scan screens
 Color, monochrome
LCD panels
Tiny, Wall-size, portables, "normal size"
3-D devices
 Head-mounted displays
 Stereo
 "Real" 3-D
Speech output
Non-speech audio
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Application Types
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Each has own unique UI style, and implementation challenges
Word processors
Drawing programs
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Painting programs
Hierarchy displays, like file browsers
Mail readers
Spreadsheets
Forms processing
WWW
Interactive games
Visualizations
Automated-teller machines (ATM)
Virtual Reality
Multi-media
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CAD/CAM
Video
Animation
Controlling machinery
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Metaphors
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Content metaphors
 desktop
 paper document
 notebook with tabs
 score sheet , stage with actors (Director)
 accounting ledger (spreadsheet)
 stereo (for all media players)
 phone keypad
 calculator
 Web: "Shopping Carts"
 Quicken: "CheckBook"
Interaction metaphors = tools, agents: "electronic secretary“
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User
Interface
Styles
(from Nielsen text)
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A method for getting information from the user or interfacing with a
user.
Usually, interfaces provide more than one style:
 Command language for experts with menus for novices
 Menus plus single characters (Macintosh & Windows)
Appropriate style depends on type of user and task.
Important issues:
 Who has control?
 Ease of use for novices.
 Learning time to become proficient
 Speed of use (efficiency) once become proficient.
 Generality/Flexibility/Power (how much of user interface with this
technique cover?)
 Ability to show defaults, current values, etc.
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 Skill requirements required (e.g., typing)
1) Question and Answer
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(Nielsen describes 1, 2 & 3 as "line-oriented”)
Computer asks questions, user answers.
Used by some simple programs, and also expert systems.
"Wizards" in Microsoft products
Telephone interfaces ("press 1 for sales, 2 for support, ...")
Pros and cons:
 + Easy to implement (writeln, readln)
 + Easy for novices
 - Can't correct previous errors, or to change your mind.
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Except in Wizards, often have a "Previous" button
- Can be slower for experts
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2) Single character commands
and/or function keys:
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Function keys can be labeled.
Pros and cons:
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+ Fastest method for experts.
+ Easy to learn how.
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+ so easier to provide telephone support ("just hit the
F1 key now")
+ Usually very simple to implement.
- Hardest to remember which key does what.
- Easy to hit wrong key by mistake
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3) Command Language:
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User types instructions to computer in a formal language.
Pros and cons:
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+ Most flexible.
+ Supports user initiative.
+ Fast for experts.
+ Possible to provide programming language capabilities for macros,
customization, etc.
+ Takes less space on screen
- Hardest for novices.
- Requires substantial training and memorization.
- Error rates usually high.
- Syntax is usually very strict.
- Poor error handling.
- Hard for user to tell what can do.
Implementation difficulty depends on availability of tools like LEX & YACC,
and the complexity of the language.
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Related form is programming language extensions, such as in Lisp.
4. Menus:
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Pros and cons:
 + Very little training needed
 + Shows available options
 + Allows use of recognition memory (easier than generation)
 + Hierarchy can expand selection
 + Default or current selection can be shown.
 + Ability to show when parts are not relevant (e.g., greyed out)
 + Can be used for commands and arguments
 + Reduces keystrokes (compared to command languages)
 + Clear structure to decision making.
 - Usable only if there are few choices
 - Slow for experienced users (need accelerators)
 - If big hierarchy, commands can be hard to find
 - Uses screen space
Most effective with pointing device.
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5) Form Filling
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Like menus except have text/number fields that can be filled in.
Often used on character terminals (e.g., for data entry).
Macintosh and Windows Dialog Boxes are another example.
Pros and cons: (Similar to menus)
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+ Simplifies data entry.
+ Very little training needed
+ Shows available options
+ Allows use of recognition memory (easier than generation)
+ Ability to show defaults and current values.
+ Ability to show when parts are not relevant (e.g., greyed out)
- Consumes screen space.
- Expensive to internationalize.
Most effective with pointing device.
Apparently, most user interfaces are of this form
Specialty of Visual Basic
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6) Direct Manipulation
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WIMP (Windows, Icons, Menus, Pointing Device) Interfaces include
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Definition:
 Visual Model of the world
 Visual objects that can be operated on
 Results of actions are reflected in the objects immediately.
 Objects, once operated on, can be further operated on.
Term coined by Ben Shneiderman
Original system: Sketchpad from 1962
"Object-oriented" from user's point of view
 As opposed to "function-oriented"
 Usually select object, then give command
 Hollan argues this user feel more important to DM than
Shneiderman's methods
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Direct Manipulation, cont.
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Pros and cons:
 + User initiated
 + Easy to learn, intuitive, analogical
 + Fast to use for object that are on the display
 + Easily augmented with menus and forms
 + Provides closure of actions and gesture.
 + Errors can be avoided.
 + High subjective satisfaction (fun).
 - Can be inconvenient and slow if user knows the name of an
undisplayed object, but must find it anyway.
 - Limited power; not all desired actions have a DM analog.
 - Difficult to provide macros, other user extensible/customizable
features.
 - Difficult to implement
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7) WYSIWYG:
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"What you see is what you get".
Like direct manipulation, but more so.
Pros and cons: (Similar to direct manipulation)
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+ Can always tell what final result will be.
- Screen image may be hard to read/interpret, especially if
screen resolution is too low.
- Cannot show hidden structure (how the picture was
made).
- May be very slow at run-time (e.g., page breaks)
- Extremely difficult to implement.
- WYSIATI: What You See Is All There Is - lack of structure;
no ability to show structure
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Next generation
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"Non-Command" or "Next-generation" or
“Post-WIMP” Interfaces
“Recognition-Based” interfaces
"Natural" actions invoke computer response.
Issues: mis-interpretation, feedback
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8) Gestures:
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Like user would mark on paper.
Pros and cons:
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+ Can be very natural to learn.
+ Often faster to execute than other techniques.
+ Give command and parameters together
- Many gestures are hard to do with a mouse.
- Users must memorize gestures.
- No "affordances“
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9) Natural Language
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E.g., a subset of normal English.
Includes speech
Pros and cons:
 + Theoretically easiest for learning.
 + Speaking is the fastest output technique.
 - Rather slow for typing
 - Requires clarification dialog.
 - Unpredictable.
 - General systems are impossible with today's technology.
Research with Bernhard Suhn showing that if factor in correction
times, speech input may be slower and less natural than typing, etc.
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Old List: What else?
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WWW
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Different style?
Pen-Based devices?
Touchscreens??
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